REP05675

• Permit No: C1982056
• IBM Index Class Name: Report
• Doc Date: 8/22/1986
• Doc Name: 1ST HALF 1986 SEMI-ANNUAL SUBSIDENCE SURVEY REPORT
• From: MLRD
• To: TWENTYMILE COAL CO
• Permit Index Doc Type: SUBSIDENCE REPORT
• Media Type: D
• Archive: No

,,
Richartl D. Lamm
Governor
DATE:
T0:
FROM:
RE:

DEPARTMENT OF NATURAL RESOURCES
David H. Getches, Executive Director

MINED LAND RECLAMATION DIVISION
DAVID C. SHELTON, Director
August 18, 1986 \
Cathy Begej ~ _
Jim Pendleton ~~
FOIDEL CREEK-MINE - 1"986 SEMI-ANNUAL SUBSIDENCE SURVEY REPORT (C-82-056)
I have completed a review of Twentymile Coal Company's first 1986 Semi-Annual
Subsidence Survey Report for the Foidel Creek Mine, certified by Michael
Joseph Astuto, Colorado Registered Land Surveyor No. 13821. This report
presents a clear and concise summary of the past half year's mechanical
subsidence and slope stability monitoring results for the Foidel Creek Mine.
To date only development of the main entries and the "FIRST SOUTH" panel have
been accomplished at the Foidel Creek Mine. No caving of the overburden has
been stimulated and no subsidence of the surface has been detected by the
monitoring program, as projected in their original permit application. The
company has installed an appropriate grid of monuments with which to monitor
possible subsidence due to the mining occurring at this time and projected to
occur within the next 6 months. The company has also surveyed the appropriate
structures; including 2 buried water tanks, the CYCC office building, an
underground gasoline storage tank, and 13 electric power poles.
The survey data represents 3 surveys of all the existing monuments and
structures at the Foidel Creek Mine site. The survey data suggest that all
monuments have been stable to date, showing no evidence of freeze/thaw or
other distorting effects.
The only monuments showing significant movement continue to be those within
the slope stability monumentation set placed at the toe of the fill slope
immediately opposite the Foidel Creek Mine portals. Monument SP-1 underwent
-0.4 feet of movement prior to its destruction in September, 1984. Monument
SP-2 has undergone -0.9 feet of movement since its installation 2 years ago;
however, no additional settlement has occurred since the second 1985
semi-annual survey was completed. In response to my concern following the
last semi-annual survey report, TCC conducted a surface reconnaissance of the
spoil slope areas adjacent to monument SP-2, on June 27, 1986, in order to
ascertain whether any evidence existed to suggest differential movement
occurring within that spoil slope. No surficial evidence of differential
movement was found on the adjoining spoil slope.
In Iqy opinion, this first 1986 semi-annual subsidence survey report submitted
by Twentymile Coal Company is clear, concise and thorough. The company
continues to do a commendable job of its mechanical subsidence monitoring at
the Foidel Creek Mine.
cc: Bob Liddle
/vj r
2936E
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]